A flat-panel CRT display consists of an electron-emitting device and a light-emitting device that operate at low internal pressure. The electron-emitting device, commonly referred to as a cathode, contains electron-emissive elements that emit electrons over a relatively wide area. The emitted electrons are directed towards light-emissive elements distributed over a corresponding area in the light-emitting device. Upon being struck by the electrons, the light-emissive elements emit light that produces an image on the viewing surface of the display.
The inside of a flat-panel display needs to be clean during display operation. Contaminants on the surfaces of the electron-emissive elements increase electron tunneling barriers. As a result, higher operating voltages are needed in the display. Also, contamination of the electron-emissive surfaces produces emission non-uniformity and instability. This leads to non-uniform brightness on the display's viewing surface. Display efficiency is reduced.
Organic materials, such as polyimide residues, are one potential source of contamination in flat-panel CRT displays. Haven, U.S. Pat. No. 5,649,847, discloses two primary display components that contain polyimide: (a) a system that focuses electrons emitted by the electron-emissive elements and (b) a "black" matrix situated around the light-emissive elements for improving image contrast. It is desirable to have an economical, environmentally safe technique for removing contaminants from a flat-panel CRT display, especially organic contaminants that arise from using materials such as polyimide in the display.